In a conventional manner, each real-time avionics system is architectured and developed so as to meet performance requirements in terms in particular of failure rate (reset) and functional Quality of Service (QoS), in a defined framework of use.
Onboard avionics systems are qualified, with a demonstrated performance level, for a given environment and have different levels of software development, that are more or less expensive, corresponding to different safety or criticality requirements. Indeed, these levels of software development arise from the aircraft risk analysis FHA (Functional Hazard Analysis), termed “operating dependability analysis”, according to the international standards RTCA DO178C (USA) or ED-12C (European equivalent of EUROCAE). This risk analysis establishes the contribution of each function in the aircraft's operational chain so as to determine which maximum failure level must be reached. In order to achieve the objective in question, the standard constrains the required quality of the hardware and software in which the function is embedded and which implements it. These development quality levels are called “DALs” (Development Assurance Levels).
Current avionics architectures are the result of a history, in which economic considerations have played a significant role. Thus, for reasons to do with “certification credit” or incremental qualification, and also for reasons to do with wiring costs relating to the interfaces, the new navigation functions have been systematically integrated within a single computer, namely either the flight management system FMS, the taxiing system TAXI or the Automatic Pilot PA.
Likewise, monitoring functions are systematically integrated within a single computer, depending on what is monitored: TCAS (Traffic Collision Avoidance System), TAWS (Terrain Awareness System), WMS (Weather Management System), the CMU (“Communication Management Unit”, airspace-related constraints), the EFB (“Electronic Flight Bag”, operational constraints of the company).
Likewise, the monitoring of the aircraft states is centralized in computers of FWS (Flight Warning Systems) and OMS (Onboard Maintenance Systems) type.
Currently, the automatic pilot PA is developed in DAL level A which corresponds to the highest safety level, and the FMS is, depending on the aircraft, developed in DAL level B or C, with a trend to switch to DAL development level B in view of its increasing use in procedures. The TCAS for its part is developed in level DAL C or DAL D, and acts as a safeguarding device, it not being used to guide the craft but to forewarn of danger when the other systems have failed.
Now, for iso-functional, that is to say for one and the same operationally rendered service, it may be estimated that each change of DAL development level multiplies the development cost tenfold. Indeed, when the software development level increases from D to A via C and B, the safety requirement increases, this being manifested by an increase in the complexity of the algorithm and its degree of validation.
Thus, a visual aid function for navigation, whose risk analysis FHA requires a level D, is currently integrated into one of the existing computers, FMS or PA, of level A to C, and this has given rise to a development cost of ten to a hundred times greater than it would have been in a level D hardware environment.
On top of this development cost, the insertion of new functions or services into an existing architecture frequently leads to complex solutions between the systems, which generate a training load for crews and maintenance teams, and increases the risk of error when operating the equipment in order to carry out the function.
Solutions are currently proposed in a first French patent application published under the number FR3013880 and a second French patent application filed on 16 May 2014 and registered under the filing number 14/01108 aimed at integrating into an avionics system, comprising a core module and a peripheral module, additional functionalities without needing to modify the software elements of the core module and using from the latter only generic services that are offered. Thus, the impact of integrating new services or functionalities on a core module of high development level such as an FMS and/or an PA is minimized.
However, the insertion of new hardware, of peripheral type, and of a lower development level than that of a core module, into existing so-called “Legacy” architectures, and supporting new functionalities of compatible development level, itself has a crippling development cost in terms in particular of the re-wiring of thousands of aircraft, the hardware integration of the new computer into the bay for interfacing it with other equipment, and its electrical power supply.
Thus, the technical problem of defining an architecture of an avionics onboard system which is more flexible and more adaptable, and which makes it possible to ensure the integration of new navigation functions at minimum cost, while guaranteeing clients the DAL level of the whole, still remains.
Thus, this need exists particularly when involved with defining a navigation architecture within an onboard navigation system with open architecture of server-client type which makes it possible to integrate a constrained aircraft route(s) optimization service.
It should be noted that the current powerful constrained route optimizers which are operationally beneficial are developed on the basis of uncertifiable software techniques that consume a great deal of computation time and memory and are unsuitable for existing avionics computers. Likewise, functions for modelling external constraints (acquisition and cropping of traffic, of the weather or of the terrain) are performed by specialized computers that cannot be integrated into a current “optimal” route computation system of FMS type.
This therefore involves redefining collaborations and functions between aircraft systems which make it possible to compute an optimal operational route under constraints of various types (traffic, terrain, weather, aircraft state, airspace, operations), which minimize the costs of integration into an open architecture navigation system whose core is a high DAL computer of FMS and/or PA type and at least one peripheral computer of lower DAL, which minimize the costs of staff training and maintenance, and which minimize more particularly the impact on the computers of high criticality (in particular the FMS whose development cost is currently among the highest of the aircraft because of its size and criticality).
The technical problem is to propose a method for operationally, functionally and physically integrating a service or application for optimizing routes under various constraints (traffic, terrain, weather, aircraft state, airspace, operations) into an onboard avionics system of “client-server” type, which minimizes the means for developing the integration of the application in terms of extra hardware, interfacing and software, of reuse of hardware, interfacing and software, of number of tasks and of hardware and software qualification time, and which minimizes the means for operating the application in terms of maintenance and staff training time, while guaranteeing the client the DAL level of the aircraft as a whole.
The technical problem is also to provide an application for optimizing route(s) of an aircraft under various constraints (traffic, terrain, weather, aircraft state, airspace, operations), which is integrated operationally, functionally and physically into an open architecture of an onboard avionics system of “client-server” type, and which minimizes the means for developing the integration of the application in terms of extra hardware, interfacing and software, of reuse of hardware, interfacing and software, of number of tasks and of hardware and software qualification time, and which minimizes the means for operating the application in terms of maintenance and staff training time, while guaranteeing the client the DAL level of the aircraft as a whole.
The technical problem is further to provide an integrating onboard avionics system with open architecture of “client-server” type which operationally, functionally and physically integrates an application for optimizing routes under various constraints (traffic, terrain, weather, aircraft state, airspace, operations) while minimizing the means for developing the integration of the application in terms of extra hardware, interfacing and software, of reuse of hardware, interfacing and software, of number of tasks and of hardware and software qualification time, and which minimizes the means for operating the application in terms of maintenance and staff training time, in compliance with the DAL level of the aircraft as a whole.
For this purpose, the subject of the invention is a method for functionally and physically integrating a constrained aircraft route(s) optimization application into an avionics onboard system, the avionics onboard system comprising:
a DAL+ digital core computer, having a first criticality level DAL+, integrated into an initial architecture of peripheral computers and databases having second criticality levels DAL−, lower than or equal to the first criticality level DAL+, and serving as server by hosting a first plurality of generic open services Serv_DAL+(j); and
a DAL− peripheral computer for managing the constrained route(s) optimization application, having a second criticality level DAL−, which is lower than or equal to the first criticality level DAL+, and serving as client by dispatching service requests to the DAL+ digital core computer and/or to the peripheral computers and databases of the initial architecture through a communications network; characterized in that the method for functionally and physically integrating the constrained route(s) optimization application comprises the steps consisting in:                functionally decomposing the constrained route(s) optimization application OPT_RTE into a second plurality of elementary functions OPT_RTE_FU(i); and        determining, on the basis of the second plurality of the elementary functions OPT_RTE_FU(i), a first list of the elementary functions that can be executed in part or entirely by at least one generic open service, and for each elementary function a first sub-list of generic open service(s); and        determining an optimal functional and physical distribution of the elementary functions OPT_RTE_FU(i) within the onboard avionics system over the set of possible distributions which minimizes a global cost criterion CG, dependent on several parameters, including at least the additional development cost of the elementary functions integrated within the DAL+ digital core computer; and        carrying out the integration of the constrained route(s) optimization application by actually implementing the elementary functions and their scheduling according to the optimal functional and physical distribution determined within the onboard avionics system in the previous step of determining the optimal functional and physical distribution of the elementary functions.        
According to particular embodiments, the method for functionally and physically integrating the application for optimizing routes under various constraints comprises one or more of the following characteristics:
the optimal functional and physical distribution of the elementary functions OPT_RTE_FU(i) within the onboard avionics system over the set of possible distributions is determined so as to minimize a first global cost criterion CG1 which takes into account only the additional development cost of the elementary functions integrated within the DAL+ digital core computer; and the integration of the constrained route(s) optimization application is carried out by actually implementing the elementary functions and their scheduling according to the optimal functional and physical distribution determined within the onboard avionics system by using the first criterion CG1;
the optimal functional and physical distribution of the elementary functions OPT_RTE_FU(i) within the onboard avionics system over the set of possible distributions is determined so as to minimize a second global cost criterion CG2 which also takes into account the development cost of the communication interfaces between the DAL+ core computer and the peripheral computers, the cost in response time and the cost of maintainability so as to minimize the communication exchanges; and the integration of the constrained route(s) optimization application is carried out by actually implementing the elementary functions and their scheduling according to the optimal functional and physical distribution determined within the onboard avionics system by using the second criterion CG2;
the optimal functional and physical distribution of the elementary functions OPT_RTE_FU(i) within the onboard avionics system over the set of possible distributions is determined so as to minimize a third global cost criterion CG3 which also takes into account the development of certain segments of code of low DAL level in the DAL+ core computer so as to minimize the complexity of the whole from the perspective of maintenance and upgrades; and the integration of the constrained route(s) optimization application is carried out by actually implementing the elementary functions and their scheduling according to the optimal functional and physical distribution determined within the onboard avionics system by using the third criterion CG3;
the optimal functional and physical distribution of the elementary functions OPT_RTE_FU(i) within the onboard avionics system over the set of possible distributions is determined so as to minimize a fourth global cost criterion CG4 which also takes into account the use of DAL+ level code libraries in the peripheral computer of DAL− level so as to minimize the use of the resources of the DAL+ core computer; and the integration of the constrained route(s) optimization application is carried out by actually implementing the elementary functions and their scheduling according to the optimal functional and physical distribution determined within the onboard avionics system by using the fourth criterion CG4;
the method for functionally and physically integrating the constrained aircraft route(s) optimization application furthermore comprises an additional step, executed after having determined an optimal functional and physical distribution of the elementary functions OPT_RTE_FU(i) within the onboard avionics system, and consisting in the constrained route(s) optimization application performance being verified and evaluated by emulation or simulation, and/or the performance of the initial services implemented on the core computer and the peripheral computers being verified;
the DAL+ digital core computer hosts services Serv_DAL+(j) for computing flight plan, lateral trajectory and temporal predictions according to a specified guidance mode, which are used for the implementation of part of the elementary functions forming the constrained route(s) optimization application; and the DAL+ digital core computer is coupled to computers for piloting the aircraft;
the first plurality of generic services Serv_DAL+(j) comprises the following services: computation of the location of the aircraft, flight plan insertion/modification, lateral trajectory computation, vertical trajectory computation, aircraft performance computation, lateral guidance, vertical guidance, guidance in terms of speed, consultation of navigation database, consultation of aircraft performance database, consultation of configuration database, consultation of magnetic declination database, display of the route and of the trajectory, display of the database elements;
the constrained aircraft route(s) optimization application comprises the following elementary functions:                A first elementary function OPT_RTE_FU(1) for selecting a “target route”;        A second elementary function OPT_RTE_FU(2) for computing the predictions along the flight plan and the trajectory        A third elementary function OPT_RTE_FU(3) for selecting the constraints to be applied;        A fourth elementary function OPT_RTE_FU(4) for selecting a minimum spacing to be complied with;        A fifth elementary function OPT_RTE_FU(5) for displaying the route and the constraints to an operator;        A sixth elementary function OPT_RTE_FU(6) for detecting conflict between the current route and the constraints;        A seventh elementary function OPT_RTE_FU(7) for displaying the navigation elements arising from the databases around the trajectory and/or around the constraints;        An eighth elementary function OPT_RTE_FU(8) for avoidance computation to resolve the conflict between the route and the constraint;        A ninth elementary function OPT_RTE_FU(9) for integrating the avoidance into the current route, intended to be reused by the second elementary function OPT_RTE_FU(2) to determine the new flight plan (the new trajectory);        A tenth elementary function OPT_RTE_FU(10) for executing the new route        An eleventh elementary function OPT_RTE_FU(11) for monitoring the evolution of the constraints at regular intervals;        
the elementary functions OPT_RTE_FU(2), OPT_RTE_FU(5), OPT_RTE_FU(7), OPT_RTE_FU(8) and OPT_RTE_FU(10) are allocated to the and implemented in the DAL+ digital core computer, while the remaining elementary functions are allocated and implemented in a DAL− peripheral computer of the system integrating the constrained route(s) optimization application;
the elementary function FIM_FU(10) which corresponds to the service Serv_DAL+(4) for the selected guidance mode and the selected navigation element is allocated to the and implemented in the digital core computer 4 DAL+, while the remaining elementary functions are allocated and implemented in a DAL− peripheral computer of the system integrating the constrained route(s) optimization application;
the elementary functions OPT_RTE_FU(2), OPT_RTE_FU(5), OPT_RTE_FU(7), OPT_RTE_FU(8) and OPT_RTE_FU(10) are allocated to the and implemented in the DAL+ digital core computer, while the remaining elementary functions are allocated and implemented in a DAL− peripheral computer of the system integrating the constrained route(s) optimization application;
the first elementary function OPT_RTE_FU(1) consists in selecting a “target route” defined by one of the following elements: a target airport, a target reference route, a portion of target reference route, a reference trajectory, a set of waypoints defined by the pilot, a set of waypoints and of navigation beacons selected from the navigation database;
the second elementary function OPT_RTE_FU(2) computes predictions along the flight plan and the trajectory, including in particular the predicted position in 3D and optionally in time of the aircraft along the trajectory, the predicted position in time making it possible to manage the dynamic or evolving constraints;
the third elementary function OPT_RTE_FU(3) selects constraints to be applied, these constraints being defined by geographical geometric shapes or raw visual representations such as volumes which model (in particular, clouds, 3D airspaces and obstacles), surfaces in 3D, especially terrain surfaces, surfaces in 2D, especially boundaries, and changes of airspaces.
The subject of the invention is also an avionics onboard system configured to implement a constrained aircraft route(s) optimization application and integrate it functionally and physically, the avionics onboard system comprising:
a DAL+ digital core computer, having a first criticality level DAL+, integrated into an initial architecture of peripheral computers and databases having second criticality levels DAL−, lower than or equal to the first criticality level DAL+, and serving as server by hosting a first plurality of generic open services Serv_DAL+(j); and
a DAL+ peripheral computer for managing the constrained route(s) optimization application, having a second criticality level DAL−, and serving as client by dispatching service requests to the DAL+ digital core computer and/or to the peripheral computers and peripheral databases of the initial architecture through a communications network;
the constrained route(s) optimization application OPT_RTE being decomposed into a plurality of elementary functions OPT_RTE_FU(i) distributed physically between the DAL+ digital core computer and the DAL− peripheral management computer according to an optimal distribution scheme determined by the method of integration defined above, and    the DAL− peripheral management computer being configured to support an application from among: an MMI, an integrated MSI, a CMU, a TCAS, a TAWS, an EFB, a tablet, a TRAFFIC COMPUTER, a dedicated generic partition; and the DAL+ digital core computer being configured to support an application from among: a flight management system FMS, an Automatic Pilot (PA), an FMGS system combining the FMS and PA functions.